My son is the same age, and will do the same thing at times. The problem is that he is taking the last drink, but not swallowing before he takes the cup out of his mouth. I have found that my son does better with a straw cup. He just had his last bottle a few days ago, and he has been doing fine honestly! I also realized that my son did not have as much dribble with the harder sippy cups, rather than the Nuby soft lids that we were using. He does the very best with the Gerber sippy cups, either with handles or the ones that "curve in" in the middle so that he can hold it. I always encourage letting go of the bottle as soon as you can because they really do become more attatched to it the older they get, but that is just me. All 3 of mine were off by 12 months or so. Good luck, he really will get better at it! ~A.~